Locked Circuits

By David Kattenburg

An estimated ten percent of Canadians struggle with depression, flashbacks and panic attacks associated with Post-Traumatic Stress Disorder (PTSD). So do 14,000 Canadian veterans – among them, retired Canadian General Romeo Dallaire, who witnessed some of the worst horrors of the 1994 Rwandan genocide.

Recent science suggests inflexible brain circuits are to blame. Getting them unstuck is the aim. At a large veterans’ hospital in Minneapolis, Minnesota, researchers have pinpointed the neural circuits that drive PTSD flashbacks and panic attacks.

“Your brain is a dynamic network,” explains Apostolos Georgopoulos, director of the hospital’s Brain Science Center. “So, when you have, let’s say a visual stimulus come in to your eyes, then the visual network that receives that information becomes temporarily locked. That individual system lasts for a few seconds, and then very quickly, becomes again ready to absorb new information.”

This is how nine of out of ten people process their experiences – be they mundane or horrific. One out of ten don’t wipe the slate clean. Dreadful sights and sounds reverberate in their heads. Dr. Georgopoulos’ lab can spot PTSD sufferers by magnetically scanning their brains.

“Healthy people [have] the ability to maintain the flexibility of their networks at various trauma strength exposures,” says Georgopoulos, describing experiments carried out in his lab. People with PTSD apparently don’t. “Their networks were locked in and could not be modulated.”

The studies Dr. Georgopoulos decribes were carried out using a sophisticated brain imaging technique called magnetoencephalography. To measure the weak magnetic signals generated by healthy and locked brain circuits, brain magnetic scans need to be carried out in a room shielded from Earth’s magnetic field. Based on a one minute scan, Dr. Georgopoulos’ team can spot inflexible PTSD circuits with 95% accuracy.

The next step? Drugs help. So do a variety of behavioral therapies aimed at getting stubborn brain circuits to unlock. “You can sort of re-package that all together and put that memory aside,” says Lisa James, a clinical psychologist at the Brain Science Center. “So it allows for their brain to de-correlate and become more flexible, so that that memory isn’t just constantly there, popping up.”

Dr. Lisa James

But PTSD flashbacks are hard to shake. The more we learn about how neural circuits recycle or get stuck, the better treatment will be.

The dividends may be huge. The locked circuits in PTSD are located in the brain’s temporal lobe, just above the right ear. The stubborn thoughts associated with neuroticism, psychosis and Obsessive-Compulsive Disorder originate elsewhere in the brain, and can also be picked up in magnetic scans. Solving the PTSD riddle may help solve these as well.